> On 10 Dec 2018, at 08:53, Shamir Rabinovitch <shamir.rabinovitch@xxxxxxxxxx> wrote:
>
> From: shamir rabinovitch <shamir.rabinovitch@xxxxxxxxxx>
>
> redundant copy_from_user in rds_sendmsg system call expose rds
> to issue where rds_rdma_extra_size walk the rds iovec and and
> calculate the number pf pages (sgs) it need to add to the tail of
> rds message and later rds_cmsg_rdma_args copy the rds iovec again
> and re calculate the same number and get different result causing
> WARN_ON in rds_message_alloc_sgs.
Am I onto something if I say that the user-data is qualified after the first copy_from_user(), and RDS assumes the validity after the second copy_form_user(), although the user-space app at this point may have fiddled with it?
> fix this by doing the copy_from_user only once per rds_sendmsg
> system call.
>
> When issue occur the below dump is seen:
>
> WARNING: CPU: 0 PID: 19789 at net/rds/message.c:316 rds_message_alloc_sgs+0x10c/0x160 net/rds/message.c:316
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 19789 Comm: syz-executor827 Not tainted 4.19.0-next-20181030+ #101
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x244/0x39d lib/dump_stack.c:113
> panic+0x2ad/0x55c kernel/panic.c:188
> __warn.cold.8+0x20/0x45 kernel/panic.c:540
> report_bug+0x254/0x2d0 lib/bug.c:186
> fixup_bug arch/x86/kernel/traps.c:178 [inline]
> do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
> do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
> invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:969
> RIP: 0010:rds_message_alloc_sgs+0x10c/0x160 net/rds/message.c:316
> Code: c0 74 04 3c 03 7e 6c 44 01 ab 78 01 00 00 e8 2b 9e 35 fa 4c 89 e0 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 14 9e 35 fa <0f> 0b 31 ff 44 89 ee e8 18 9f 35 fa 45 85 ed 75 1b e8 fe 9d 35 fa
> RSP: 0018:ffff8801c51b7460 EFLAGS: 00010293
> RAX: ffff8801bc412080 RBX: ffff8801d7bf4040 RCX: ffffffff8749c9e6
> RDX: 0000000000000000 RSI: ffffffff8749ca5c RDI: 0000000000000004
> RBP: ffff8801c51b7490 R08: ffff8801bc412080 R09: ffffed003b5c5b67
> R10: ffffed003b5c5b67 R11: ffff8801dae2db3b R12: 0000000000000000
> R13: 000000000007165c R14: 000000000007165c R15: 0000000000000005
> rds_cmsg_rdma_args+0x82d/0x1510 net/rds/rdma.c:623
> rds_cmsg_send net/rds/send.c:971 [inline]
> rds_sendmsg+0x19a2/0x3180 net/rds/send.c:1273
> sock_sendmsg_nosec net/socket.c:622 [inline]
> sock_sendmsg+0xd5/0x120 net/socket.c:632
> ___sys_sendmsg+0x7fd/0x930 net/socket.c:2117
> __sys_sendmsg+0x11d/0x280 net/socket.c:2155
> __do_sys_sendmsg net/socket.c:2164 [inline]
> __se_sys_sendmsg net/socket.c:2162 [inline]
> __x64_sys_sendmsg+0x78/0xb0 net/socket.c:2162
> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x44a859
> Code: e8 dc e6 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 6b cb fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007f1d4710ada8 EFLAGS: 00000297 ORIG_RAX: 000000000000002e
> RAX: ffffffffffffffda RBX: 00000000006dcc28 RCX: 000000000044a859
> RDX: 0000000000000000 RSI: 0000000020001600 RDI: 0000000000000003
> RBP: 00000000006dcc20 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000297 R12: 00000000006dcc2c
> R13: 646e732f7665642f R14: 00007f1d4710b9c0 R15: 00000000006dcd2c
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
> Reported-by: syzbot+26de17458aeda9d305d8@xxxxxxxxxxxxxxxxxxxxxxxxx
> Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>
> Signed-off-by: shamir rabinovitch <shamir.rabinovitch@xxxxxxxxxx>
> ---
> net/rds/rdma.c | 63 +++++++++++++++++++++++++-------------------------
> net/rds/rds.h | 20 ++++++++++++----
> net/rds/send.c | 47 +++++++++++++++++++++++++++++++------
> 3 files changed, 88 insertions(+), 42 deletions(-)
>
> diff --git a/net/rds/rdma.c b/net/rds/rdma.c
> index 98237feb607a..e1965d9cbcf8 100644
> --- a/net/rds/rdma.c
> +++ b/net/rds/rdma.c
> @@ -517,9 +517,10 @@ static int rds_rdma_pages(struct rds_iovec iov[], int nr_iovecs)
> return tot_pages;
> }
>
> -int rds_rdma_extra_size(struct rds_rdma_args *args)
> +int rds_rdma_extra_size(struct rds_rdma_args *args,
> + struct rds_iov_vector *iov)
> {
> - struct rds_iovec vec;
> + struct rds_iovec *vec;
> struct rds_iovec __user *local_vec;
> int tot_pages = 0;
> unsigned int nr_pages;
> @@ -530,13 +531,23 @@ int rds_rdma_extra_size(struct rds_rdma_args *args)
> if (args->nr_local == 0)
> return -EINVAL;
>
> + iov->iov = kcalloc(args->nr_local,
> + sizeof(struct rds_iovec),
> + GFP_KERNEL);
> + if (!iov->iov)
> + return -ENOMEM;
> +
> + vec = &iov->iov[0];
> +
> + if (copy_from_user(vec, local_vec, args->nr_local *
> + sizeof(struct rds_iovec)))
> + return -EFAULT;
> + iov->len = args->nr_local;
> +
> /* figure out the number of pages in the vector */
> - for (i = 0; i < args->nr_local; i++) {
> - if (copy_from_user(&vec, &local_vec[i],
> - sizeof(struct rds_iovec)))
> - return -EFAULT;
> + for (i = 0; i < args->nr_local; i++, vec++) {
>
> - nr_pages = rds_pages_in_vec(&vec);
> + nr_pages = rds_pages_in_vec(vec);
> if (nr_pages == 0)
> return -EINVAL;
>
> @@ -558,15 +569,15 @@ int rds_rdma_extra_size(struct rds_rdma_args *args)
> * Extract all arguments and set up the rdma_op
> */
> int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> - struct cmsghdr *cmsg)
> + struct cmsghdr *cmsg,
> + struct rds_iov_vector *vec)
> {
> struct rds_rdma_args *args;
> struct rm_rdma_op *op = &rm->rdma;
> int nr_pages;
> unsigned int nr_bytes;
> struct page **pages = NULL;
> - struct rds_iovec iovstack[UIO_FASTIOV], *iovs = iovstack;
> - int iov_size;
> + struct rds_iovec *iovs;
> unsigned int i, j;
> int ret = 0;
>
> @@ -586,31 +597,23 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> goto out_ret;
> }
>
> - /* Check whether to allocate the iovec area */
> - iov_size = args->nr_local * sizeof(struct rds_iovec);
> - if (args->nr_local > UIO_FASTIOV) {
> - iovs = sock_kmalloc(rds_rs_to_sk(rs), iov_size, GFP_KERNEL);
> - if (!iovs) {
> - ret = -ENOMEM;
> - goto out_ret;
> - }
> + if (vec->len != args->nr_local) {
> + ret = -EINVAL;
> + goto out_ret;
> }
>
> - if (copy_from_user(iovs, (struct rds_iovec __user *)(unsigned long) args->local_vec_addr, iov_size)) {
> - ret = -EFAULT;
> - goto out;
> - }
> + iovs = vec->iov;
>
> nr_pages = rds_rdma_pages(iovs, args->nr_local);
> if (nr_pages < 0) {
> ret = -EINVAL;
> - goto out;
> + goto out_ret;
> }
>
> pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
> if (!pages) {
> ret = -ENOMEM;
> - goto out;
> + goto out_ret;
> }
>
> op->op_write = !!(args->flags & RDS_RDMA_READWRITE);
> @@ -623,7 +626,7 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> op->op_sg = rds_message_alloc_sgs(rm, nr_pages);
> if (!op->op_sg) {
> ret = -ENOMEM;
> - goto out;
> + goto out_pages;
> }
>
> if (op->op_notify || op->op_recverr) {
> @@ -635,7 +638,7 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> op->op_notifier = kmalloc(sizeof(struct rds_notifier), GFP_KERNEL);
> if (!op->op_notifier) {
> ret = -ENOMEM;
> - goto out;
> + goto out_pages;
> }
> op->op_notifier->n_user_token = args->user_token;
> op->op_notifier->n_status = RDS_RDMA_SUCCESS;
> @@ -681,7 +684,7 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> */
> ret = rds_pin_pages(iov->addr, nr, pages, !op->op_write);
> if (ret < 0)
> - goto out;
> + goto out_pages;
> else
> ret = 0;
>
> @@ -714,13 +717,11 @@ int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> nr_bytes,
> (unsigned int) args->remote_vec.bytes);
> ret = -EINVAL;
> - goto out;
> + goto out_pages;
> }
> op->op_bytes = nr_bytes;
>
> -out:
> - if (iovs != iovstack)
> - sock_kfree_s(rds_rs_to_sk(rs), iovs, iov_size);
> +out_pages:
> kfree(pages);
> out_ret:
> if (ret)
> diff --git a/net/rds/rds.h b/net/rds/rds.h
> index 6bfaf05b63b2..42f4350444f6 100644
> --- a/net/rds/rds.h
> +++ b/net/rds/rds.h
> @@ -386,6 +386,18 @@ static inline void rds_message_zcopy_queue_init(struct rds_msg_zcopy_queue *q)
> INIT_LIST_HEAD(&q->zcookie_head);
> }
>
> +struct rds_iov_vector {
> + struct rds_iovec *iov;
> + int len;
> +};
> +
> +struct rds_iov_vector_arr {
> + struct rds_iov_vector *vec;
> + int len;
> + int ind;
> + int inc;
Would it be possible to use more descriptive names here for ind and inc? "inc" is often used as an instantiation of struct rds_incoming. Or is it increment? Is ind "index"?
> +};
> +
> struct rds_message {
> refcount_t m_refcount;
> struct list_head m_sock_item;
> @@ -904,13 +916,13 @@ int rds_get_mr(struct rds_sock *rs, char __user *optval, int optlen);
> int rds_get_mr_for_dest(struct rds_sock *rs, char __user *optval, int optlen);
> int rds_free_mr(struct rds_sock *rs, char __user *optval, int optlen);
> void rds_rdma_drop_keys(struct rds_sock *rs);
> -int rds_rdma_extra_size(struct rds_rdma_args *args);
> -int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> - struct cmsghdr *cmsg);
> +int rds_rdma_extra_size(struct rds_rdma_args *args,
> + struct rds_iov_vector *iov);
> int rds_cmsg_rdma_dest(struct rds_sock *rs, struct rds_message *rm,
> struct cmsghdr *cmsg);
> int rds_cmsg_rdma_args(struct rds_sock *rs, struct rds_message *rm,
> - struct cmsghdr *cmsg);
> + struct cmsghdr *cmsg,
> + struct rds_iov_vector *vec);
> int rds_cmsg_rdma_map(struct rds_sock *rs, struct rds_message *rm,
> struct cmsghdr *cmsg);
> void rds_rdma_free_op(struct rm_rdma_op *ro);
> diff --git a/net/rds/send.c b/net/rds/send.c
> index fe785ee819dd..b23e0b999beb 100644
> --- a/net/rds/send.c
> +++ b/net/rds/send.c
> @@ -876,13 +876,15 @@ static int rds_send_queue_rm(struct rds_sock *rs, struct rds_connection *conn,
> * rds_message is getting to be quite complicated, and we'd like to allocate
> * it all in one go. This figures out how big it needs to be up front.
> */
> -static int rds_rm_size(struct msghdr *msg, int num_sgs)
> +static int rds_rm_size(struct msghdr *msg, int num_sgs,
> + struct rds_iov_vector_arr *vct)
> {
> struct cmsghdr *cmsg;
> int size = 0;
> int cmsg_groups = 0;
> int retval;
> bool zcopy_cookie = false;
> + struct rds_iov_vector *iov;
>
> for_each_cmsghdr(cmsg, msg) {
> if (!CMSG_OK(msg, cmsg))
> @@ -893,8 +895,21 @@ static int rds_rm_size(struct msghdr *msg, int num_sgs)
>
> switch (cmsg->cmsg_type) {
> case RDS_CMSG_RDMA_ARGS:
> + if (vct->ind >= vct->len) {
> + vct->len += vct->inc;
> + vct->vec =
> + krealloc(vct->vec,
> + vct->len *
> + sizeof(struct rds_iov_vector),
> + GFP_KERNEL);
Here you will leak memory, because you loose the pointer to what you already have allocated. You must do something aka:
tmp = krealloc();
if (!tmp) {
kfree(vct->vec);
return -ENOMEM;
}
vct->vec = tmp;
With that,
Acked-by: Håkon Bugge <haakon.bugge@xxxxxxxxxx>
Thxs, Håkon
> + if (!vct->vec)
> + return -ENOMEM;
> + }
> + iov = &vct->vec[vct->ind];
> + memset(iov, 0, sizeof(struct rds_iov_vector));
> + vct->ind++;
> cmsg_groups |= 1;
> - retval = rds_rdma_extra_size(CMSG_DATA(cmsg));
> + retval = rds_rdma_extra_size(CMSG_DATA(cmsg), iov);
> if (retval < 0)
> return retval;
> size += retval;
> @@ -951,10 +966,11 @@ static int rds_cmsg_zcopy(struct rds_sock *rs, struct rds_message *rm,
> }
>
> static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
> - struct msghdr *msg, int *allocated_mr)
> + struct msghdr *msg, int *allocated_mr,
> + struct rds_iov_vector_arr *vct)
> {
> struct cmsghdr *cmsg;
> - int ret = 0;
> + int ret = 0, ind = 0;
>
> for_each_cmsghdr(cmsg, msg) {
> if (!CMSG_OK(msg, cmsg))
> @@ -968,7 +984,10 @@ static int rds_cmsg_send(struct rds_sock *rs, struct rds_message *rm,
> */
> switch (cmsg->cmsg_type) {
> case RDS_CMSG_RDMA_ARGS:
> - ret = rds_cmsg_rdma_args(rs, rm, cmsg);
> + if (ind >= vct->ind)
> + return -ENOMEM;
> + ret = rds_cmsg_rdma_args(rs, rm, cmsg, &vct->vec[ind]);
> + ind++;
> break;
>
> case RDS_CMSG_RDMA_DEST:
> @@ -1084,6 +1103,11 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
> sock_flag(rds_rs_to_sk(rs), SOCK_ZEROCOPY));
> int num_sgs = ceil(payload_len, PAGE_SIZE);
> int namelen;
> + struct rds_iov_vector_arr vct = {0};
> + int ind;
> +
> + /* expect 1 RDMA CMSG per rds_sendmsg. can still grow if more needed. */
> + vct.inc = 1;
>
> /* Mirror Linux UDP mirror of BSD error message compatibility */
> /* XXX: Perhaps MSG_MORE someday */
> @@ -1220,7 +1244,7 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
> num_sgs = iov_iter_npages(&msg->msg_iter, INT_MAX);
> }
> /* size of rm including all sgs */
> - ret = rds_rm_size(msg, num_sgs);
> + ret = rds_rm_size(msg, num_sgs, &vct);
> if (ret < 0)
> goto out;
>
> @@ -1270,7 +1294,7 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
> rm->m_conn_path = cpath;
>
> /* Parse any control messages the user may have included. */
> - ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
> + ret = rds_cmsg_send(rs, rm, msg, &allocated_mr, &vct);
> if (ret) {
> /* Trigger connection so that its ready for the next retry */
> if (ret == -EAGAIN)
> @@ -1348,9 +1372,18 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
> if (ret)
> goto out;
> rds_message_put(rm);
> +
> + for (ind = 0; ind < vct.ind; ind++)
> + kfree(vct.vec[ind].iov);
> + kfree(vct.vec);
> +
> return payload_len;
>
> out:
> + for (ind = 0; ind < vct.ind; ind++)
> + kfree(vct.vec[ind].iov);
> + kfree(vct.vec);
> +
> /* If the user included a RDMA_MAP cmsg, we allocated a MR on the fly.
> * If the sendmsg goes through, we keep the MR. If it fails with EAGAIN
> * or in any other way, we need to destroy the MR again */
> --
> 2.19.1
>
